1. Field
The invention relates to a positioning device which in particular has a positioning accuracy within the submillimeter range.
Positioning devices having positioning accuracies within the submillimeter range are used in a multiplicity of applications in research and industry. To achieve a high positioning accuracy, systems having as few mechanical parts as possible and having a high quality of the surfaces in the region of mechanical guides and engagements must be used. In addition to as high a reproducibility and scalability of paths of movement as possible, properties such as insensitivity to vibrations, robustness and compactness of the construction in practical use play an essential role. In addition, the operability of such positioning devices is also often to be maintained under extreme conditions, such as, for example, low temperature, ultrahigh vacuum (UHV) or high electrical or magnetic fields.
2. Description of the Related Art
Various types of construction of positioning devices are known. A known type of construction which both permits a high positioning accuracy and is in principle suitable for use under extreme conditions uses an “inertia motor”, which is also referred to as a slip-stick drive. Slip-stick drives are based on the principle of a mechanical friction clutch which works within the range of the static friction in a first relative direction of movement between the clutch parts frictionally in engagement and works within the range of the sliding friction in the opposite relative direction of movement. This results in a translatory movement between the two clutch parts, wherein the direction and the increment of the translatory movement can be set via suitable activation of an actuator of the slip-stick drive.
Slip-stick drives are usually sensitive and can be easily damaged by shock. In particular, the actuator which is often designed as a piezoelectric element can fracture or sustain damage in another way. Experience shows that shock effects often occur on account of improper handling during assembly of the positioning device in the desired application or also during transport, e.g. by the positioning device falling to the ground.